The AviationNow site has a story on someone by the name Dan O'Dowd who is saying Linux and all OpenSource applications are security threats to the U.S. Department of Defense. O'Dowd is quoted in the article saying:
If Linux is compromised, our defenses could be disabled, spied on or commandeered," O'Dowd said at an April 8 panel during the NetCentric Operations 2004 conference sponsored by the Association of Enterprise Integration and held in McLean, Va. "Every day, new code is added to Linux in Russia, China and elsewhere throughout the world. Every day, that code is incorporated into our command, control, communications and weapons system. This must stop.
It may not be a coincidence that O'Dowd works for a company that sells a proprietary operating systems supposedly designed for defense systems. But that is not to say people don't have to audit changes made to OpenSource initiatives for security concerns but, in my opinion, it's a long way to saying all OpenSource is less secure than his or any other proprietary offering.